Regulators of Formation and Properties of Nanofilled Polypropylene Threads

Abstract

The influence of the content of silica nanoparticles and the combined substances, namely, aluminium oxide/silica and zinc oxide/silica, on the rheological properties of the polypropylene (PP) melt and the characteristics of modified monothreads is studied. As established, the effective viscosity of PP/nanofiller compositions increases in the entire concentration range studied (0.1–3.0 wt.%) and depends on the chemical nature of the additive. In the presence of silica, the viscosity of melts increases by 20%; when mixed ZnO/SiO2 and Al2O3/SiO2 oxides are added, it increases by 30% and 50%, respectively. The elasticity of all the investigated systems decreases with increasing content of additives, judging by the indicators of jet swelling. The ability to process nanofilled compositions is improved, as evidenced by an increase in the maximum deformation of the melt jet in the longitudinal tensile field. The presence of silica nanoparticles and mixed oxides in the structure of PP monothreads improves their operational characteristics: the breaking strength and modulus of elasticity increase by 1.3–1.5 times, the percentage of strength retention in the loop and knot increases, and shrinkage decreases. Modified threads, like a polypropylene, are monolithic, have a smooth surface and are uniform in diameter along their length. Nanofillers containing a metal-oxide phase on the surface are more effective compared to the original silica.